[{"title":"(1个子文件12.04MB)北京邮电大学804信号与系统历年考研真题及参考答案","children":[{"title":"北京邮电大学804信号与系统历年考研真题及参考答案","children":[{"title":"北京邮电大学804信号与系统历年考研真题及参考答案.pdf <span style='color:#111;'>13.08MB</span>","children":null,"spread":false}],"spread":true}],"spread":true}]